04/04/2022
Medulloblastoma
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A medulloblastoma is a specific type of brain tumour which mainly affects children. This information should ideally be read with our general information about brain tumours and children’s cancers. If you are an adult with a medulloblastoma, most of the information will still be relevant to you.
•Brain tumours
•Medulloblastomas
•Causes of a medulloblastoma
•Signs and symptoms of a medulloblastoma
•Tests and investigations for medulloblastoma
•Treatment for medulloblastoma
More people than ever are surviving cancer. There are new and better drugs and treatments available. But it remains devastating to hear that you or your child has cancer, and at times it can feel overwhelming. There are many healthcare professionals and support organisations to help you through this difficult time.
The central nervous system (CNS) is made up of the brain and spinal cord. Cells within the brain normally divide and grow in an orderly and controlled way, but if for some reason this process gets out of control, the cells continue to divide and form a lump called a tumour.
A tumour is either benign or malignant. Benign tumours can continue to grow, but the cells do not spread from the original site. In a malignant tumour, the cells can invade and destroy surrounding tissue and may spread to other parts of the brain.
Tumours affecting the central nervous system (CNS) are fairly rare. In the UK, around 5,000 people are diagnosed with a malignant brain tumour each year.
Medulloblastomas are malignant tumours formed from poorly developed cells at a very early stage of their life. They develop in the cerebellum (see diagram below) in a part of the skull called the posterior fossa, but may spread to other parts of the brain.
Very rarely, medulloblastomas may spread to other parts of the body. If they do spread to other parts of the brain or to the spinal cord, this is usually through the cerebrospinal fluid (CSF). CSF is the fluid that surrounds and protects the brain and the spinal cord.
Tumours affecting the central nervous system (CNS), which is made up of the brain and spinal cord, are fairly rare. About 4,500 new tumours are diagnosed each year in the UK. Many of these are malignant.
Medulloblastomas are more common in children, particularly between the ages of three and eight. They make up about 1 in 5 (20%) of all childhood brain tumours. The tumour is more common in boys than girls. They rarely occur in adults.
Causes of a medulloblastoma
The cause of medulloblastoma is unknown. Researchers are trying to discover possible causes.
Signs and symptoms of a medulloblastoma
The first symptoms of any brain tumour are usually due to increased pressure within the skull (raised intracranial pressure). This may be caused by a blockage in the ventricles (fluid-filled spaces in the brain), which leads to a build-up of CSF. The increased pressure can also be caused by swelling around the tumour itself.
Raised intracranial pressure can cause headaches, sickness (vomiting) and sight problems. Vomiting is common first thing in the morning. Children often appear tired, weak and irritable. There can also be changes in personality and behaviour.
The cerebellum is the part of the brain that controls muscle coordination, and a tumour in this area may cause problems with walking. A person may appear to stumble, or walk in an awkward or uncoordinated way. Speech can also be affected, and words may be slurred or muddled.
Other symptoms that can happen with medulloblastoma are nystagmus (jerky eye movements), neck stiffness and muscle weakness. The specific symptoms that people have will depend on the size and position of the tumour.
Tests and investigations for medulloblastoma
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(computerised tomography) scan
A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless and takes 10–30 minutes. CT scans use small amounts of radiation, which will be very unlikely to harm your child or anyone they come into contact with. A CT scan may be used to identify exactly where the tumour is or to check for any spread of the cancer.
Most people who have a CT scan are given an injection or drink first, which allow particular areas to be seen more clearly on the scan. This may make your child feel hot all over. Before having the injection or drink, it is important to tell the person doing this test if your child is allergic to iodine or has asthma.
(magnetic resonance imaging) scan
An MRI scan is similar to a CT scan but uses magnetism instead of x-rays to build up cross-sectional pictures of your child's body. Often the brain and whole spinal cord are scanned.
Before having the scan, you'll be asked to remove any metal belongings from your child, including jewellery. Some children are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan show up more clearly. During the test your child will be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It is painless but can be slightly uncomfortable, and some children feel a bit claustrophobic during the scan. It's also noisy, but your child can listen to a CD or wear earplugs.
A sample of cells from the tumour (biopsy) is usually taken and examined under a microscope. The biopsy involves an operation. The doctor will discuss with you whether this is needed and exactly what the operation involves.
puncture
A lumbar puncture is carried out to see if there are any tumour cells present in the cerebrospinal fluid (CSF). The skin on your child's back is numbed with local anaesthetic, and a hollow needle is inserted between two of the spinal bones and into the spinal canal. A small amount of spinal fluid can be withdrawn for tests. MRI scans can also show the presence of any tumour in the spinal cord.
Treatment for medulloblastoma
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The treatment for medulloblastoma depends on a number of factors, including child's general health, and the size and position of the tumour. The results of the tests will enable the doctor to decide on the best type of treatment.
Child's treatment will usually be planned by a team of specialists known as a multidisciplinary team (MDT).
The team will usually include:
• a doctor who operates on the brain (neurosurgeon)
• a doctor who specialises in treating illnesses of the brain (neurologist)
• a doctor who specialises in treating brain tumours (an oncologist)
• a specialist nurse
• other healthcare professionals, such as a physiotherapist or dietitian.
Consent
Before child has any treatment, doctor will give full information about the aims of the treatment and what it involves. They will usually ask to sign a form saying that you give permission (consent) for the hospital staff to give the treatment to child. No medical treatment can be given without consent. There are some risks associated with treatment to the brain and the doctor will discuss these.
Benefits and disadvantages of treatment
Treatment can be given for different reasons and the potential benefits will vary for each child. If your child has been offered treatment that aims to cure the cancer, deciding whether your child has the treatment may not be difficult. However, if a cure is not possible and the treatment is to control the cancer for a period of time, it may be more difficult to decide whether to go ahead.
If you feel that you can’t make a decision about the treatment when it is first explained, you can always ask for more time to decide.
Treatment is often given at an important time in your child’s development. There may be some long-term effects of treatment for medulloblastoma, including hearing problems, growth and hormonal changes, behavioural changes and possible learning difficulties. The doctor will discuss the possible long-term effects with you before treatment.
Surgery
If your child has raised intracranial pressure, steroid drugs may be given to reduce swelling around the tumour. At the beginning of the operation a tube (shunt) may need to be inserted into the area to drain off the excess fluid.
The aim of surgery is to remove as much of the tumour as possible, without damaging the surrounding brain tissue. It is rarely possible to remove the tumour completely, so surgery will be followed up with radiotherapy and/or chemotherapy.
After surgery for medulloblastoma, a CT scan or MRI scan may be done to find out how much of the tumour is left.
Radiotherapy
Radiotherapy treatment uses high energy rays to destroy the cancer cells. It is commonly used after surgery to destroy any remaining malignant cells. As medulloblastoma may spread through the CSF to the spinal cord, radiotherapy is given to the brain and spinal cord. This may be followed by a booster dose to the part of the brain where the medulloblastoma was originally found.
Whenever possible, radiotherapy is not given to children under three years old. This is to allow further development of the brain and spinal cord, and to reduce the risk of long-term side effects. Instead, a course of chemotherapy is given and, if necessary, radiotherapy is given when the child is older.
There can be a risk of developing late side effects from radiotherapy. The doctors will be able to explain more about this.
Chemotherapy
Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. It may be given alone to treat medulloblastoma, or with surgery and radiotherapy.
Side effects may include increased risked of infection, tiredness, hair loss, feeling sick and a sore mouth. The doctor or nurse will be able to tell you more about the side effects your child may experience during treatment, and ways of managing them.
